Electromagnetic relays are used extensively as electromechanical switches in various applications such as electrical circuit boards, alarms, and sensors etc. Typically, a relay comprises an electromagnet with a soft iron bar, or armature. A movable contact/switch is coupled to the armature such that the contact is held in its normal position by e.g. a return spring. Typically, when the electromagnet is energized, by e.g. a user applying a power source to the relay, a magnetic force overcomes the biasing force provided by the return spring and moves the contact into an alternative position, such that the circuit is either open or connected. When the electromagnet is de-energized, by e.g. a user removing the power source to the relay, the contact returns to and is held in its normal position by the return spring.
In some electromagnetic relays, a lock-down door and test button is provided, where manual or physical manipulation of the relay switch can be provided and the manipulated position of the switch physically retained. The manipulation thus bypasses the effect of the electromagnet within the relay. In other words, some relays are integrated with an assembly which allows for the manual operation of the switch, without having to energize the electromagnet coil. This can allow a user to e.g. debug a system controlled by the relay, without energizing the relay's coil.
However, such integrated lock-down door and test button assemblies are not always present in all electromagnetic relays. Non-provision of such assemblies can be because the presence of such additional assemblies may add to the cost of the electromagnetic relay. Further, such assemblies cannot be easily incorporated in certain types of relays due to size or other constraints defined by industrial standards or user requirements. This is particularly true for a range of relays, typically called slim relays. In relays where the lock-down door and test button assemblies cannot be provided, e.g. in conventional slim relays, there does not exist any means for switching the relay to another state without some form of energizing the coil. This situation is particularly difficult and undesirable given that relays, after manufacturing, are typically encapsulated by a moulding material and the internal components of the relay, such as the coil and armature, are not typically accessible. Furthermore, for debugging purposes, it is also not desired to energize a relay in order to switch its state. For example, relays can be used to control a high-power circuit using a low-power signal, with complete electrical isolation between the control and controlled circuits. During commissioning or debugging of the relay, there are situations where the low power signal supplied to the coil cannot or should not be provided.
Therefore, there exists a need for a tool for switching the state of a relay that seeks to address at least one of the above problems.